Nebraska's decision Monday on permits for the Keystone XL project won't be affected by a major oil spill this week because state law bars regulators from factoring in the risks of pipeline spills when considering pipelines, experts say.

Opponents of the Keystone XL oil pipeline, a proposed addition to TransCanada's pipeline system, have used Thursday's 210,000 gallon spill in South Dakota to raise new concerns about the safety of the proposed line.

But Doug Hayes, a senior attorney for the Sierra Club's Environmental Law Program, said Nebraska law bars the Public Service Commission from considering similar risks when permitting new pipelines.

"The law the [Public Service Commission] is operating under says they shouldn't consider the risk of oil spills," he said.

Still, he said, "It's hard to believe they won't hear about this massive spill. It's one of the biggest concerns to Nebraskans."

Nebraska law considers oil spill prevention a federal issue, not a state one, meaning state regulators are not tasked with considering the risks, The Associated Press reported Friday.

TransCanada reapplied for a permit to build Keystone XL through Nebraska in February. Since then, the Public Service Commission has heard testimony and taken public comment on the issue, and announced this week that it would make a decision on the proposed pipeline on Monday.

A Public Service Commission spokeswoman told the AP on Friday that the decision "will be based on the evidence in the record," which includes testimony, documents and more than a half-million public comments.

Thursday's Keystone spill gave opponents of the expansion a new reason to cast doubt on the project, with many green groups releasing statements urging Nebraska regulators - a board of five elected commissioners - to vote down the pipeline.

The commission's announcement is not the last word on Keystone: Not only is the decision subject to legal appeals, but federal officials still have to issue permits for the project, and green groups are suing against previous approval decisions both federally and in South Dakota.

TransCanada also has to determine if the pipeline is economically viable. Officials have said they hope to begin construction on the project sometime next year.

The company said Friday morning that it has more than 75 workers responding to the Keystone spill in Marshall County, S.D. Officials said there is no threat to public safety, and that they're working with state and federal regulators to assess work on the pipeline.